Multiple explosions at a steel plant near Pittsburgh have killed two people and left 10 others injured on Monday, according to authorities.

The mill, which is part of the recent merger between U.S. Steel and Nippon Steel, has faced scrutiny from federal and local regulators.

The explosion rocked the Clairton Coke Works, about 10 miles south of downtown Pittsburgh and one of four U.S. Steel plants in PA.

Investigators were working Tuesday to determine the cause of the blast, which jolted a region of the state synonymous with steel for more than a century.

A devastating explosion at a steel plant near Pittsburgh left two dead and 10 injured. The blast, whose cause is still under investigation, shook the region synonymous with steel production. Concerns about safety and air quality have been heightened as officials and environmental groups demand a thorough investigation.

The explosion, followed by several smaller blasts, could be felt in the nearby community and prompted county officials to warn residents to stay away from the scene so emergency workers could respond.

CLAIRTON, Pa. (TNND) — An investigation is ongoing after two people were killed and 10 were injured in an explosion at a U.S. Steel plant near Pittsburgh on Monday, leaving behind smoldering rubble and plumes of black smoke.